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Downloaded from jcp.bmj.com on 24 March 2008 p53 protein expression and genetic mutation in two primary cell types in pulmonary sclerosing haemangioma Y Wang, S-D Dai, F-J Qi, H-T Xu and E-H Wang J. Clin. Pathol. 2008;61;192-196; originally published online 17 Aug 2007; doi:10.1136/jcp.2007.050401 Updated information and services can be found at: http://jcp.bmj.com/cgi/content/full/61/2/192 These include: References Rapid responses Email alerting service This article cites 23 articles, 6 of which can be accessed free at: http://jcp.bmj.com/cgi/content/full/61/2/192#BIBL You can respond to this article at: http://jcp.bmj.com/cgi/eletter-submit/61/2/192 Receive free email alerts when new articles cite this article - sign up in the box at the top right corner of the article Notes To order reprints of this article go to: http://journals.bmj.com/cgi/reprintform To subscribe to Journal of Clinical Pathology go to: http://journals.bmj.com/subscriptions/ Downloaded from jcp.bmj.com on 24 March 2008 Original article p53 protein expression and genetic mutation in two primary cell types in pulmonary sclerosing haemangioma Y Wang, S-D Dai, F-J Qi, H-T Xu, E-H Wang Department of Pathology, College of Basic Medical Sciences, China Medical University and Department of Pathology, First Affiliated Hospital of China Medical University, Shenyang 110001, China Correspondence to: Dr En-Hua Wang, Department of Pathology, College of Basic Medical Sciences, China Medical University and Department of Pathology, First Affiliated Hospital of China Medical University, Shenyang 110001, China; wangeh@ hotmail.com Accepted 2 August 2007 Published Online First 1 October 2007 ABSTRACT Aims: To investigate the significance of p53 protein expression and genetic mutations in two primary cell types in pulmonary sclerosing haemangioma (PSH). Methods: p53 protein expression in polygonal cells and cuboidal cells in 19 patients with PSH was detected using immunohistochemistry. The two major cell types were captured using laser capture microdissection technology. Mutations in the p53 gene (exons 5–8) were examined using single-stranded conformation polymorphism and DNA sequencing analysis. Results: p53 protein expression and gene mutations were observed in 15.8% (3/19) of cases. In these cases, p53 protein was expressed in the nucleus of both cell types, with higher expression levels and mutation rates in polygonal cells than in surface cuboidal cells. Two cases showed mutation only in the polygonal cells, while one case showed double (separate) mutations in both the polygonal and cuboidal cells. Conclusions: p53 mutation was exhibited in PSH. The mutation rate in polygonal cells was higher than that in surface cuboidal cells. Pulmonary sclerosing haemangioma (PSH) is a rare pulmonary tumour of unknown origin, although the histological characterisation and biological behaviour of PSH have long been a focus of research.1–5 PSH is widely believed to be a benign tumour because of its clinical course; however, Miyagawa-Hayashino et al6 reported metastases in approximately 2–4% of PSH cases, necessitating further exploration of the development and progression of this tumour. Mutations in the p53 gene, and associated p53 protein accumulation, are the most common events associated with the development and clinical progression of malignant tumours.7–12 Several authors have detected expression of p53 mRNA and protein in PSH, although their findings differed significantly.5 13 14 In the present study, we evaluated expression of the p53 protein in two types of cells affected by PSH via streptavidin peroxidase immunohistochemistry. Mutations in the p53 gene were detected by single-stranded conformation polymorphism (SSCP) and sequencing analyses, providing data for investigating the biological behaviour of PSH. METHODS Subjects Paraffin-embedded PSH samples and normal lung tissue adjacent to PSH were obtained from 19 patients (two men and 17 women) who were 192 diagnosed with PSH at the First Clinical College of China Medical University between 1995 and 2004. This study was conducted according to the regulations of the institutional review boards (China Medical University). The age range was 24–46 years, and the mean age was 34.5 years. Of the 19 patients, 12 had no symptoms and their PSH was found upon routine examination; the other seven patients presented with symptoms including chest pain, cough and bloody phlegm. x Rays or CT scans revealed unitary masses, frequently in the periphery of the lungs. These masses were round or oval and of high density, with a smooth boundary, and with no burs or lobules. The masses were located in the right lung in 11 cases and the left lung in eight cases. The follow-up time (after surgery, to December 2005) ranged from 13–129 months; all patients survived, without recurrence or metastasis. Immunohistochemistry Formalin-fixed paraffin-embedded tissue blocks were cut into 4 mm sections, de-waxed and hydrated. Immunostaining was performed with the streptavidin peroxidase system (Ultrasensitive; MaiXin, Fuzhou, China) according to manufacturer’s instructions. The sections were incubated with a primary anti-p53 antibody (DO-7, dilution 1:50; Santa Cruz Biotechnology, Santa Cruz, California, USA). Biotinylated goat anti-mouse serum IgG was used as a secondary antibody. After washing three times in phosphate-buffered saline (PBS), the sections were incubated with streptavidin-biotin conjugated with horseradish peroxidase, and visualised by demonstration of conjugated peroxidase with diaminobenzidine as the substrate. The sections were counterstained with haematoxylin. For the negative control, primary antibodies were replaced with PBS; for the positive control, known positive tissue was used. A slide was considered negative or positive according to the absence or presence of positive staining: no staining or fewer than 5% of total cells positive for p53 was considered negative; greater than 5% of total cells positive for p53 was considered positive staining. Laser capture microdissection of target cells, and extraction of DNA The paraffin-embedded samples were sectioned successively at a thickness of 6 mm. The sections were subjected to Mayer’s H&E staining, dehydration with gradient alcohol, and lucidification with xylene (for 5 min). After drying, the sections were J Clin Pathol 2008;61:192–196. doi:10.1136/jcp.2007.050401 Downloaded from jcp.bmj.com on 24 March 2008 Original article placed onto the object stage of an inverted microscope connected to a laser capture microdissection system (model LM200; Olympus, Tokyo, Japan). The target cells were identified with an orientating beam and then captured by a laser beam. A total of 5000–10000 surface cuboidal cells and polygonal cells were captured (fig 1). A 0.5-ml centrifuge tube containing 50 ml DNA lysis buffer (10 mmol/l Tris HCl, pH8.0; 1 mmol/l EDTA, pH 8.0; 1% Tween 20; 200 mg/ml proteinase K) was incubated at 48uC for 14 h, proteinase K was deactivated at 95uC for 10 min, and the tube was stored 220uC until further analysis. PCR-SSCP and sequencing PCR reaction mixture (50 ml) containing 10 ml DNA isolated from polygonal or surface cuboidal cells served as a template, and was mixed with 1 ml primers (30 pmol/ml; 5–8 exons), 0.4 ml Taq polymerase, 4 ml dNTP, and 5 ml 106 PCR buffer. The PCR conditions included initial denaturing at 94uC for 2 min, then 40 cycles at 94uC for 40 s, after which samples were subjected to annealing (see table 1 for temperatures and times), and a final extension at 72uC for 1 min. The PCR products (4 ml) were loaded onto a 2% agarose gel to confirm successful amplification and non-specific bands, followed by SSCP analysis. The PCR product (6 ml) was mixed with an equal volume of loading dye and denatured at 100uC for 10 min, and placed on ice for 5 min. The samples were then separated on 10% non-denaturing polyacrylamide gel (49:1). For each condition, we used adjacent normal lung tissue as a control. After electrophoresis, the gel was fixed, silver-stained, developed, photographed and analysed. The sample was considered normal if the band position was the same as that of the normal tissue. The same PCR products were used for sequencing (Shanghai United Gene Biotechnology, Shanghai, China). RESULTS Gross and histological study The nodules were 1.4–4.9 cm in diameter and were well circumscribed with or without capsule. They were medium soft and often had a pale-brown region caused by haemorrhage. The tumour showed expansive growth pattern without multiple masses, infiltration and metastasis in any case. Histologically, all cases showed varying degrees of solid, papillary, haemorrhagic and sclerotic patterns. The tumours were composed entirely of polygonal and cuboidal cells. Polygonal cells were located in the solid and papillary areas, which had faintly stained or eosinophilic cytoplasm, round or oval nuclei, and small nucleoli, but rare or no karyomitosis. Surface cuboidal cells covered the papilla or were located in the Table 1 p53 primer sequences, length of amplified fragments and PCR annealing temperatures Exon Primer sequence 5 59-GCTGCCGTGTTCCAGTTGCT-39 59-CCAGCCCTGTCGTCTCTCCA-39 59-TTGCTCTTAGGTCTGGCCCC-39 59-CAGACCTCAGGCGGCTCATA-39 59-TAGGTTGGCTCTGACTGTACC-39 59-TGACCTGGAGTCTTCCAGTGT-39 59-TATCCTGAGTAGTGGTAATC-39 59-AAGTGAATCTGAGGCATAAC-39 6 7 8 Product size PCR annealing temperature and time 294 bp 61uC, 40 s 127 bp 58.8uC, 40 s 116 bp 58.8uC, 40 s 213 bp 51uC, 40 s Figure 1 Laser captured pulmonary sclerosing haemangioma (PSH) polygonal cells and surface cuboidal cells. (A) PSH tissue, showing cuboidal cells on the papillary surface and polygonal cells in the stroma, (H&E, not mounted). (B) PSH tissue after laser capture of papillary surface cuboidal cells. (C) Papillary surface cuboidal cells captured by laser from PSH tissue. (D) PSH tissue, showing polygonal cells in the solid areas (H&E, not mounted). (E) PSH tissue after laser capture of polygonal cells. (F) Polygonal cells captured by laser from PSH tissue. J Clin Pathol 2008;61:192–196. doi:10.1136/jcp.2007.050401 193 Downloaded from jcp.bmj.com on 24 March 2008 Original article interspaces of the haemorrhagic areas and in the lacuna spaces of the solid areas. These cells were mostly cuboidal, and some were thin and flat, or cylindrical. These cells had merged into multinucleated giant cells,3 but did not present as heteromorphic. Infiltration of inflammatory cells such as lymphocytes, infiltrated haemosiderin deposition, calcification, and ossification could be observed in the interstitium (fig 2A–F). Immunohistochemistry p53 protein expression was observed in both cell types in three out of the 19 PSH tissue samples (15.8%), with more immunoreactive polygonal cells than immunoreactive surface cuboidal cells (fig 3). Of the other 15 samples showing no p53 protein expression, one case exhibited immunoreactivity, but in fewer than 5% of cells. There was no p53 protein expression in any samples of normal lung tissue. SSCP and sequencing analyses As shown in table 2, the SSCP analysis and DNA sequencing revealed that abnormal mobility bands and mutations were observed in three p53-immunoreactive cases, with a mutation rate of 15.8% (fig 4A,B). A mutation in the p53 gene occurred in exon 6 in one case, and exon 7 in two cases. No mutations were found in exons 5 and 8. Two cases showed mutation only in the polygonal cells, while one case shows double (separate) mutations in both the polygonal and cuboidal cells. Four missense mutations were identified and their amino acid sequences were predicted (table 2). DISCUSSION It is generally believed that PSHs are benign tumours because of a clear demarcation of the haemangioma from surrounding tissues, low cellular heteromorphism, rare or no karyomitosis, and good clinical prognosis. However, some authors classify PSH as a potential malignant tumour because the tumour tissue has been found to infiltrate the surrounding interstitium or bronchi, and because local lymph node metastasis of the tumour has been reported.1 6 15–21 Although several markers, including cytokeratin, Vimentin, carcinoembryonic antigen and surfactant protein A, are differentially expressed in polygonal cells and surface cuboidal cells in PSH, and there are characteristic lamellar bodies in surface cuboidal cells, both types of cell can express epithelial membrane antigen and thyroid transcription factor 1. Because thyroid transcription factor 1 can be specifically expressed in the fetal lung epithelial cell nuclei, it is thought that both types of cells derive from primitive respiratory epithelium, and that the Figure 2 Histomorphological changes in pulmonary sclerosing haemangioma (PSH). PSH is composed of sclerotic (A, upper left), hemorrhagic (A, lower right), solid (B), and papillary (C) areas. Papillary surface cuboidal cells (C) were not immunoreactive to Vimentin but immunoreactive to surfactant protein B; these cells occasionally fused into multinucleated giant cells (D). There are many mast cells (F) and widespread calcification (E). 194 J Clin Pathol 2008;61:192–196. doi:10.1136/jcp.2007.050401 Downloaded from jcp.bmj.com on 24 March 2008 Original article Figure 3 p53 protein expression in pulmonary sclerosing haemangioma (PSH). (A) Significantly more polygonal cells were p53 immunoreactive than cuboidal cells in PSH (streptavidin peroxidase immunostaining, 6400). (B) The PSH sample from case 2 was not p53 immunoreactive (cells with immunoreactive nuclei ,5%) (streptavidin peroxidase immunostaining, 6400). differences in their morphological phenotype are due to disparate differentiation states.1 2 22 However, it remains unknown whether the two cell types behave similarly in vivo. To further investigate the role of these two cell types in PSH, we studied the cell-specific expression of the p53 gene, a gene that is heavily implicated in human tumourigenesis. Previous reports suggest that approximately 50% of human tumours are associated with mutations in, or overexpression or loss of heterozygosity of, the p53 gene.7 8 Greenblatt et al18 studied the p53 gene sequence related to human tumours and found that approximately 87% of p53 gene mutations occur in exons 5–8. Based on these findings, we investigated potential mutations in exons 5–8 of the p53 gene in PSH tissue. The present results demonstrate that the p53 protein is expressed in 15.8% of the PSH samples, with a higher expression in polygonal cells than in surface cuboidal cells. The SSCP and sequencing analyses demonstrated that p53 gene mutations occurred in both cell types, with a higher gene mutation rate in polygonal cells than in surface cuboidal cells. We have also found with the same tissue samples that E-cadherin, b-catenin, and p120ctn are abundantly expressed on surface cuboidal cell membrane, but are poorly or not expressed in polygonal cell cytoplasm,23 suggesting a marked formation of the cad–cat complex in the former and a lack of formation of the cad–cat complex in the latter. These findings support the hypothesis that the two cell types are at different differentiation states, and may help explain why polygonal cells, rather than surface cuboidal cells, have been observed in PSH metastases.2 6 15 p53 gene sequencing revealed an mutation rate of 15.8% (3/ 19) in PSH, a figure that confirms the positive rates for the SSCP and immunohistochemical analyses. The results suggest that PSH exhibits potential malignant biological behaviour and may help explain the clinical findings of occasional infiltration and metastasis of PSH. In summary, the finding of p53 mutations in a small number of PSH is supportive of PSH being a neoplastic process. p53 gene Figure 4 Mutations in exon 7 in the polygonal cells of the pulmonary sclerosing haemangioma sample from case no. 14, as demonstrated by the single-stranded conformation polymorphism (SSCP) and sequencing analyses. (A) SSCP analysis of exon 7 of the p53 gene in normal lung tissue (N) and samples. Polygonal cells (P) show abnormal mobility bands. M, marker; C, surface cuboidal cells. (B) p53 exon 7 sequencing. No mutations were found in surface cuboidal cells (C) while a mutation was identified in polygonal cells (P) of case no. 14, GCCRGGC (ie, glycineRalanine). J Clin Pathol 2008;61:192–196. doi:10.1136/jcp.2007.050401 195 Downloaded from jcp.bmj.com on 24 March 2008 Original article Table 2 p53 Mutation and expression analysis of pulmonary sclerosing haemangioma p53 gene sequence Case no. Cell type SSCP Exon, mutation Predicted effect 8 Polygonal Cuboidal Polygonal Cuboidal Polygonal Cuboidal Shift band None Shift band Shift band Shift band None 6, GTGRGCG 5–8, none 7, ATCRTTC 7, AACRACC 7, GGCRGCC 5–8, none V197A None I232L N247C G244A None 12 14 No. of cited db p53 protein expression 6 6 137 43 22 22 + – + + + – No. of cited db, number of times the mutation has been found in human cancers in the p53 database.24 6. Take-home messages 7. c c We investigated p53 protein expression and genetic mutations in two primary cell types in pulmonary sclerosing haemangioma using laser capture microdissection, immunohistochemistry, single-stranded conformation polymorphism and DNA sequencing. The key findings of our work were that we discovered the p53 mutation exhibited in pulmonary sclerosing haemangioma, and that the mutation rate in polygonal cells was higher than in surface cuboidal cells. 8. 9. 10. 11. 12. mutations were found to occur in PSH, and does this indicate potential malignant biological behaviour of this type of PSH? The question requires further support from future investigations with larger sample sizes and case follow-up, particularly cases with lymph node metastases and recurrent PSH. 13. 14. 15. Competing interests: None. Ethics approval: Ethics committee approval was obtained. REFERENCES 1. 2. 3. 4. 5. 196 Devouassoux-Shisheboran M, Hayashi T, Linnoila RI, et al. 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